Complete heart block in children admitted to the pediatric intensive care unit with respiratory syncytial viral (RSV) infections has been described. This report describes a prolonged sinoatrial block exceeding 4 s in an infant with RSV, which, to the authors' knowledge, is the longest such event described in the published literature. This block was followed by shorter episodes within the next 24 h. An extensive workup showed no other known cause of bradycardia or sinoatrial block. The infant was discharged home with 48 h Holter monitoring, which was normal. At this writing, the infant has remained asymptomatic since discharge. Respiratory syncytial viral infections may cause prolonged sinoatrial block in an otherwise healthy child.